This invention relates to an ultrasonic probing apparatus, and more particularly to an ultrasonic probing apparatus of the type for probing tubular members of piping to detect any flaws, which is suitable for carrying out testing in those portions of the piping in which the spacing between the tubular members is small.
In a nuclear power plant, ultrasonic probing of the tubular members of its complex system of pipes is carried out to ascertain the flawlessness of the piping in maintenance and inspection immediately after the nuclear power plant is built and also after the plant is shut down. In carrying out maintenance and inspection following the shutdown of the nuclear power plant, the objects to be inspected exist in radioactive atmosphere, and thus there arises the need to use a remotely controlled automatic ultrasonic probing apparatus (hereinafter referred to simply as an ultrasonic probing apparatus) to eliminate the danger of exposing the operator for effecting ultrasonic probing to radiation. Programs are now under way in various quarters for developing ultrasonic probing apparatus. In ultrasonic probing apparatus, severe restrictions are placed on their weight and bulk and a high degree of precision is required in carrying out tests.
In a nuclear power plant, pipes of complicated pipe system are arranged close together and the spacing between the pipes is naturally small. Therefore, one of the important problems that should be solved for ultrasonic probing apparatus is how to reduce the height of the apparatus sufficiently to avoid the collision of the apparatus against the adjacent pipe in moving the apparatus circumferentially of the pipe to be probed for any flaws that might be present therein. If the ultrasonic probing apparatus had a large height, movement of the apparatus circumferentially of a pipe would be interfered with, thereby making it impossible to effect ultrasonic probing of pipes to detect flaws.
One example of ultrasonic probing apparatus is disclosed in U.S. Pat. No. 3,921,440 in which a guide rail is mounted around a pipe to be tested, and a driving member is arranged on the guide rail for movement therealong. An arm having a probing means at its forward end is mounted on the driving member for movement along the axis of the pipe. The driving member has also mounted thereon a swinging mechanism for moving the probing means in swinging movement in a horizontal plane. The aforesaid parts constitute a driving unit of the ultrasonic probing apparatus. The probing means is provided with an angle varying mechanism for varying the angle of incidence of ultrasonic sound waves incident on the surface to be probed. The driving member is provided with a circumferentially driving mechanism for moving the probing means circumferentially of the pipe to be probed and an axially driving mechanism for moving the probing means axially of the pipe, as well as the swinging mechanism for the probing means. Moreover, the angle varying mechanism is mounted in the probing means, so that the driving means has a very great height. Thus, in this ultrasonic probing mechanism, difficulties would be encountered in moving the probing means circumferentially of the pipe to be probed.